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SCHEDULE II - VALUATION ACCOUNTS (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Accounts receivable, allowance for doubtful accounts |  |  |
Valuation accounts |  |  |
Balance at Beginning of Period | $ 949 | $ 787 | $ 912
Additions Charged (Credited) to Expense | 1,610 | 162 | (125)
Balance at End of Period | 2,559 | 949 | 787
Deferred tax valuation allowance |  |  |
Valuation accounts |  |  |
Balance at Beginning of Period | 806 | 1,280 | 1,280
Additions Charged (Credited) to Expense | (154) | (474) |
Balance at End of Period | $ 652 | $ 806 | $ 1,280

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- Definition Amount of valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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- Definition Amount of increase in valuation and qualifying accounts and reserves from charge to cost and expense. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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